AI-generated descriptions ("Letra" / "Chorus" / "Translation") landed
in the DB with markdown prefixes that the sanitiser treated as plain
text — so viewers saw literal "## Letra" and "### Chorus" instead of
headings.
HtmlSanitizer::render() now promotes `##` / `###` at the start of a
line into <h2>/<h3> before sanitising, so the existing allowlist
accepts them and the reader sees real headings. Only touches lines
whose entire content is a heading — markdown mid-sentence is left
alone to avoid false positives.
Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>
